Thermostat



Feb. 26 ,1924. 1,484,802

G. F. TAYLOR THERMOSTAT Filed Dec. 13, 1923 rarement rea. ze, i924.

STATES orifice.

GEORGE F. TAYLOR, OF WASHINGTON, DISTRICT OF COLUMBIA, DEDICATED, BY MESNE ASSIGNMENTS, TO THE CITIZENS 0F THE UNITED STATES OF AMERICA.

THERMOSTAT.

Application led December 13, 1923. Serial No. 680,473.

(FILED UNDER THE ACT O MARCH 3, 1883, 22 STAT. L., 625.) Y

T 0 all wh-0m' it may concern:

Be it known that I. Gnoizcn F. TAYLOR, a citizen of the United States of America, and an employee of the United States Department of Agriculture, residing in lashington` District of Columbia, have invented a new and useful Thermostat.

This application is made under the act of March 3, 1883, chapter H3 (22 Stat. 625) and the invention herein described and claimed may be used by the Government of the United States or any of its oiiicers or employees in the prosecution of work for the Government, 0r by any citizen of the United States, without payment to me of any royalty thereon. l

The object of my invention is to provide a device by the application of which veither automatic temperature control or automatic temperature recording may be secured.

The invention will be fully described in connection with the accompanying drawing in which Fig. l shows a front elevation of the entire apparatus; Fig. 2 is a vertical sectional view thereof;,Fig. 3 is an enlarged fragmentary vert-ical sectional view illustrating the key way of the grooved pin engaged by the keys, carried by the knurled nut housing; Fig. 4 is a perspective view of the grooved pin, and Fig. 5 is an enlarged fragmentary vertical sectional view illustrating the method of sealing the container tap.

A is a tube with a bulb B at its upper end. To the lower end of the tube A is attached a rubber sack S. Just above this sack S a brass collar C fits securely around the glass tube A and screws into the expansion bulb D. P represents a spherical piston madeJ of steel, bone or other substance which does not amalgamate with mercury. The stem E of the piston is attached to the sphere and extends through the bulb B. y

When the apparatus is in use the expansion bulb D is filled with alcohol, ether, or other liquid of high coefiicient of expansion which does not injure rubber. The rubber sack S and the lower part of the tube A are filled with mercury. A rise of temperature in th'e liquid in the bulb D is accompanied by an increase in volume, which forces the mercury out of the rubber sack S into the tube A. A small air space is left around the sphere P. The surface tension of the mercury being` very high, will cause the mercury to force the piston P upward, rather than low around it. A lowering of the temperature in the bulb D will produce the reverse effect due to the atmospheric pressure on the surface of the mercury in A. The movement of the piston stem E may be employed to operate either a thermostat, a thermoregulator, or a thermograph.

The accompanyingrv drawing shows a thermostat, and illustrates the way in which it is operated by the device just described.

G is a frame which supports the entire apparatus, W and W are pivots on which the bulb D with its attached parts may be turned for greater convenience in filling or cleaning. The lock screws X hold the bulb and parts in their normal position. Q, is a threaded and grooved pin which is raised or lowered by turning the nut M. On the lower end of the pin Q, two springs K are attached opposite each other. They are electrically insulated from each other and from the frames G. Each spring is connected by a wire O to a bindin post N, the latter attached to the frame ut insulated from it. Between the springs are two contact points I. A small roller R made of an insulating material is attached to the end of each spring K. The plunger E is wedge shaped at its upper end and tits between shallow grooves in the rollers R. When the plunger E moves upward due to a rise of temperature in the bulb D (described above), the rollers R are forced apart and the contacts I are separated. This breaks an electric current which iiows through heating coils (not shown in figure) and the temperature falls. The reverse movements now take place and the temperature is held at a fixed point.

If the temperature to be controlled or recorded must be at a distance from the controlling or recording device, a capillary metallic tube not shown) may be inserted between the bu b D and the tube A.

In this device the advantages of mercury in temperature regulating instruments are combined with those of the more ex ansive liquids. It will be noted that no fou ing of the mercury can take place in the working parts. The only occur is on the sur ace of the mercury, where lace where oxidation can it is of no consequence. It will be noted that the mercury is used only 'as a medium to transmit motion and that no electrical contact is made with it; also that shaking or jarring;r has no significant effect upon the operation of the instrument.

The electrical contacts in this thermostat are as heavy as those of an ordinary relay. llt may therefore be used directly on an ordinary alternatin current lighting circuit Without the use o a relay.

l claim:

A thermostat consisting 'of a frame, a tube and an expansion llulb supported by said frame, said tube havin an enlargement at its upper end and a rub er sack at its lower end, a spherical piston ttin loosely into 'said tube, a stem attached to said piston at its mariene lower end and (intending:Ir upwardly through said tube, said expansion bulb adapted to enclose said sack, said lower portion of said tubo containing mercury, a small air Space provided in said tube around said piston. said sack and lower end of said tube being; hermetically sealed into said expansion bulb, said expansion bulb containing liquid, said piston and stem adapted to be moved in an upward or downward direction b v means of motion imparted thereto by the rising or falling of the mercury in said'tube resulting from compression or the release of compression on the mercury due to the expansion 0r contraction of the liquid in said expansion bulb.

GEORGE F. TAYLQR. 

